9to5mac has reported that devs are finding code in the soon-to-be-released iOS 6.1 that point towards a new device, featuring 128GB of storage. Adding some fuel to that fire is a new set of SKUs, leaked by a "high-profile U.S. retailer", which point to a new "ultimate" version of the iPad.
In the past Apple has referred to its storage options as "Good," "Better," and "Best", so the use of the "Ultimate" signifier could suggest a premium iPad is waiting in the wings—potentially offering up that rumored 128GB of storage.
It's possible, then, that Apple is adding an extra model to its existing iPad range—perhaps for special customers or internal use, given its large capacity, which is expensive and doesn't fit with the growing trend of migrating to the cloud. Another possibility is that Apple is giving its whole iPad range a light spring-time spruce up—though that seems rather less likely.
The final option, of course, is that it's all speculation that amounts to nothing. We'll have to hold on and see. More here.